Much concern has arisen in recent years about persons introducing foreign objects into food containers that are placed for sale in stores. As a result, it is highly desirable to provide assurance to a customer that no unauthorized tampering with the closure member has occurred prior to purchase. In manufacturing closures, it has oftentimes been the practice to provide some form of special cut or slit or scores in the material of the closure so as to enhance tearing of the material of the closure at a pregiven location to evidence that the lid has been tampered with. Manufacturing techniques require, therefore, a separate cutting step or slitting step or scoring step in order to cause the closure to have the requisite characteristics providing tamper evidence when an attempt is made to remove the closure from a food container. Conversely, the food packer will use auxiliary heat shrinkable bands, heat sealed foils or adhesive labels to provide the tamper evident feature. It is desired to provide a closure which does not require the aforesaid special cuts and/or slits and/or scores and does not require the use of any bands, labels and the like, and yet provide the desirable tamper-evident characteristics for the package.
It is an object of this invention to provide a thermoplastic closure for an open topped container having tamper-evident characteristics without necessitating additional machining thereto, such as providing cutout notches and/or slits and/or scoring in the material of the closure or the use of auxiliary bands, labels and the like.
It is a further object of this invention to provide a closure, as aforesaid, which has the requisite resistance to material tearing but yet evidences tampering by a tearing of the material once a force is applied to the closure in an effort to remove it from the container.